Benzofuran dyes containing a coumarin nucleus

ABSTRACT

A 6-tertiary amino-2-(Z═CH--)benzofuran dye is disclosed, where Z represents the atoms providing an electron withdrawing group and a conjugated methine linkage completing a resonant dye chromophore including the 6-tertiary amino group as an electron donor and the electron withdrawing group as an electron acceptor. The dyes are formed by condensing a 6-tertiary amino-2-formylbenzofuran with an electron withdrawing dye nucleus precursor containing an active methyl or methylene site. The dyes exhibit bathocromically shifted absorption peaks.

This is a division of U.S. Ser. No. 191,948, filed May 9, 1988, now U.S.Pat. No. 4,900,831.

FIELD OF THE INVENTION

The invention relates to certain novel dyes. More specifically, theinvention relates to benzofuran dyes containing novel chromophores.

PRIOR ART

Grychtol U.S. Pat. No. 3,932,446 discloses a 6-aminobenzofuran dye whichis substituted in its 2 position with a cyano group, a carboxy acid orester group, or a electron donating nucleus, such as a benzoxazole,benzothiazole, or benzimidazole.

Specht et al U.S. Pat. No. 4,278,751 discloses a ketocoumarincoinitiator for free radical polymerization having a maximum absorptionin the 350 to 550 nm range containing a 7-amino substituent to thecoumarin ring. The 7-amino substituent can complete a Julolidene ringfused with the coumarin ring.

RELATED PATENT APPLICATIONS

Farid et al U.S. Ser. Nos. 933,712, 933,658, 933,660, and 933,657, allfiled Nov. 21, 1986, now issued as U.S. Pat. Nos. 4,743,528, '529, '530,and 531, and commonly assigned, disclose hardenable compositionscomprised of an organic compound containing ethylenic unsaturation, anazinium salt activator, and, acting as a photosensitizer, a dye having areduction Potential which is at most 0.1 more positive than thereduction potential of the azinium salt activator.

Chen et al U.S. Ser. No. 191,947, filed May 9, 1988 and commonlyassigned, titled DYE SENSITIZED PHOTOGRAPHIC IMAGING SYSTEMS, now U.S.Pat. No. 4,876,175, discloses imaging systems containing certain of thedyes of this invention employed as photosensitizers.

SUMMARY OF THE INVENTION

In one aspect, this invention is directed to a 6-tertiaryamino-2-(Z═CH--)benzofuran, where Z represents the atoms providing anelectron withdrawing group and a conjugated methine linkage completing aresonant dye chromophore including the 6-tertiary amino group as anelectron donor and the electron withdrawing group as an electronacceptor.

The present invention has as its purpose to provide a 6 tertiaryaminobenzofuran dye containing a novel chromophore. Specifically, thedyes of the present invention contain a resonant dye chromophore whichlinks the electron donating 6-amino substituent with an electronaccepting second nucleus chosen from any of a variety of known electronaccepting nuclei. As a result, the invention makes possible 6-tertiaryaminobenzofuran dyes having longer wavelength absorption peaks andproperties better suited to a variety of applications. Both fluorescentdyes and dyes capable of acting as coinitiators for free radicalpolymerization are within the contemplation of this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

This invention is directed to a 6-tertiary aminobenzofuran dyecontaining a novel chromophore produced by providing at the 2 positionof the furan ring a substituent satisfying the formula: (I)

    --CH═Z

where

Z represents the atoms providing an electron withdrawing group and aconjugated methine linkage completing a resonant dye chromophoreincluding the 6-tertiary amino group as an electron donor and theelectron withdrawing group as an electron acceptor.

The dyes of the present invention contain a resonant chromophore whichcan be represented by the resonance extremes: ##STR1## where R₂represent any convenient choice of substituents to complete a tertiaryamine;

L², L³, L^(3a), L⁴, L⁵, and L⁶ represent methine groups provided by thebenzofuran nucleus, where the superscript corresponds the ring site atwhich the methine group is located;

═L--(L═L)_(n) -W corresponds to Z;

L is independently in each occurrence an optionally substituted methinegroup;

n is zero or a positive integer, typically 4 or less; and

W is an electron acceptor. In keeping with established practice, thevarious forms of dye structures are named by reference to the unchargedresonance extreme represented by Formula IIa.

The dyes of the present invention can be Prepared by employing a6-tertiary amino 2-formyl benzofuran as a starting material. The6-tertiary amino 2-formylbenzofuran can be condensed with a precursor ofZ at an active methyl or methylene site. In other words, the novelchromophore can be formed by the reaction: (III)

    6TABF-CHO+H.sub.2 Z'→6TABF-C═Z+H.sub.2 O

where

6TABF-CHO represents a 2-formyl-6-(tertiary amino)benzofuran and

H₂ Z' is an active methyl or methylene precursor of Z.

From the simplicity of the condensation reaction it is apparent that Zcan take a wide range of forms and Permitting both the chromophore andthe physical properties of the dye to be tailored to specificapplication requirements.

The description which follows is directed to certain preferred,illustrative forms of the dyes. The terms "alkyl" and "aryl" areemployed throughout to indicate substituents that can be widely varied.In general it is preferred to choose alkyl substituents from among thosethat contain 1 to 8 carbon atoms. Aryl substituents preferably containfrom 6 to 10 carbon atoms--e.g., phenyl or naphthyl. To minimizemolecular bulk lower alkyl groups (those containing from 1 to 3 carbonatoms--i.e., methyl, ethyl, and propyl) and phenyl groups are optimumsubstituent choices satisfying the alkyl and aryl substituentdefinitions, respectively.

In a preferred form 2-(6-tertiary-amino)-benzofuranyl nucleus of the dyecan be represented by the following formula: (IV) ##STR2## where R¹, R²,and R⁵ each independently represent hydrogen, alkyl, or aryl and

R³ and R₄ each independently represent alkyl; or

at least one of the substituent pairs represented by R¹ and R⁴, R² andR³, and R³ and R⁴ complete a 5- or 6-membered ring.

For example, R¹ and R₂, when independent of the amino group, and R⁵ arepreferably hydrogen, but substituent variations, such as, phenyl,methyl, ethyl, propyl, and the like are readily accomodated on the ringstructure. R³ and R⁴, when present as independent substituents, arepreferably alkyl, such as methyl or ethyl. R³ and R⁴ can together formany convenient 5- or 6-membered ring structure, such as morpholino orpiperidino. Generally increased stability and bathochromic shifts in dyehue are realized when at least one of the two pairs represented by R¹and R⁴ or R² and R³ combine to complete a 5- or 6-membered ring, whichpreferably contains the amino nitrogen atom as the sole heteroatom, suchas a pyrrole, pyrroline, indole, indoline, or piperidine ring.

In a specifically preferred form of the benzofuran nucleus both the R¹and R⁴ and R² and R³ substituent together form a julolidine group. Whilethe Julolidine groups are illustrated below as unsubstituted groups, itis appreciated that substituents are possible. For example, one or twobenzo rings can be readily fused with the Julolidine ring.

The Present dyes are made possible by the discovery of processes forpreparing the 2-formyl-6-(tertiary amino)benzofuran intermediate. WhenR⁵ is hydrogen, the intermediates can be prepared by

(1) condensation of a 2-hydroxybenzaldehyde having a nitrogensubstituent in the 4-position with methyl bromoacetate and sodiumhydride to produce the methyl ester of a 2-carboxybenzofuran,

(2) reduction of the ester to the alcohol with lithium aluminum hydride,and

(3) reoxidation of the alcohol to the aldehyde with manganese dioxide orp chloranil.

The preparation is illustrated in the following reaction scheme:##STR3##

When R⁵ is other than hydrogen--e.g., alkyl or aryl, the intermediatescan be prepared by

(1) reacting o-aminophenol with R⁵ bromomethyl ketone in the presence ofpotassium carbonate,

(2) employing zinc chloride to effect ring closure by the eliminationwater, and

(3) achieving formyl substitution by the Vilsmeir reaction employingphosphoryl chloride and dimethylformamide (DMF).

The preparation is illustrated in the following reaction scheme:##STR4##

Although omitted for simplicity from the exemplary schematic reactionsequences, it is appreciated that in either synthetic approach R¹, R²,R³, and R⁴ can be present and can take any of the forms described above.

Widely different choices of Z to complete the chromophore are possible,depending upon the application to be served. To illustrate the breadthof the invention, exemplary forms of Z are discussed by reference to twomutually exclusive classes of dyes: first to dyes which form highlyefficient coinitiators for free radical polymerization and then tofluorescent dyes.

In one preferred form the dyes of the invention contain a coumarinnucleus These dyes can be represented by the formula: (V) ##STR5## where##STR6## R¹ represents ##STR7## and R¹³ represents a 3-coumarinyl group.The coumarin nucleus can be selected from any of a variety of knownforms, such as those disclosed is Specht et al. U.S. Pat. No. 4,278,751,the disclosure of which is here incorporated by reference.

Preferred coumarin nuclei are those which are substituted in ringposition 7 with an amino group, subsequently referred to as a 7-aminosubstituent When the 7-amino substituent is a tertiary amine, it canform an extension of the dye chromophore in a manner similar to thatdescribed above in connection with 6-amino substituent of thebenzofuranyl nucleus. Thus, the preferred 3-coumarinyl groups can berepresented by the formula: (VI) ##STR8## where R₆ and R₇ eachindependently represent hydrogen, alkyl, or aryl;

R⁸ and R⁹ each independently represent alkyl; or

at least one of the substituent pairs represented by R⁶ and R⁹, R⁷ andR⁸, and R⁸ and R⁹ complete a 5- or 6-membered ring.

The preferences discussed above in connection with selections of R¹, R²,R³, and R⁴ are applicable to selections of R⁶, R⁷, R⁸, and R⁹,respectively.

In another preferred form the dyes of the invention can take the form ofbis[2-(6-amino)benzo furanyl] dyes in which the benzofuran nuclei sharea common electron withdrawing moiety in the chromophore, such as W,described above. This again has the effect of lengthening andstabilizing the chromophore.

Exemplary bis[2-(6-amino)benzofuranyl] dyes useful as coinitiators forfree radical polymerization and crosslinking are those represented bythe formula: (VII) ##STR9## where E¹ and E² are independently2-(6-amino)benzo furanyl groups and

X¹ and X² are independently hydrogen, alkyl, or aryl or togethercomplete a 5 to 7 membered ring.

When X¹ and X² are independently selected, forms such as hydrogen,phenyl, methyl, or ethyl are preferred.

When X¹ and X² together complete a 5 to 7 membered ring, they preferablycomplete a ring satisfying the formulae: (VIII)

    --(CH.sub.2).sub.n --

or (IX)

    --(CH.sub.2 --Y--CH.sub.2)--

where

n is 2 to 4;

Y is --NR¹⁰ -- or 0 ;

R¹⁰ is hydrogen, lower alkyl, or Phenyl.

In the simplest form the ring can be a carbocyclic ring, such ascyclopentanone, cyclohexanone, or cycloheptanone. A functionallycompatible heteroatom, such as nitrogen (e.g., --NR¹⁰ --) or oxygen(i.e., --O--), can be substituted for one or more of the ring carbonatoms. Preferred heterocyclic rings for these bis[2-(6-amino)benzofuranyl] dyes are those in which piperidin 4-one andtetrahydropyran-4-one rings form the central ring.

While dyes which contain a conjugated carbonyl or sulfonyl moiety actingas an electron acceptor for the chromophore form superior coinitiatorsfor free radical polymerization, dyes which contain cyano (i.e., --CN)electron acceptors in the chromophore are generally recognized to formsuperior fluorescent dyes.

A very simple dye structure results when Z takes the form of adicyanomethylene group. Preferred forms of such dyes are those whichsatisfy the formula: (X) ##STR10## where R¹, R², R³, R⁴, and R⁵preferably take the forms previously discussed.

Highly efficient fluorescent dyes are those which contain adicyanomethylenepyran or dicyanomethylenethiopyran nucleus in thechromophore. Preferred dyes of this type can be represented by theformula: (XI) ##STR11## where E¹ is a 2-(6-amino)benzofuranylsubstituent;

Q is oxygen or sulfur; and

R¹¹ is alkyl, aryl, or --CH═CH--E¹.

When R¹¹ also includes E¹, it is apparent that these dyes can also bebis[2-(6-amino)benzofuranyl] dyes.

Although the above illustrative have been selected to illustrate thepresence of a sulfonyl or carbonyl electron accepting moiety or a cyanoelectron accepting moiety in the dye chromophore, it is possible toproduce dyes according to the invention which contain both types ofelectron accepting groups in the same chromophore. Such dyes areillustrated by reference to a preferred class of dyes according to theinvention which include in addition to the basic 2-(6-amino)benzofuranylnucleus a furan 2-one-5-yl-idene nucleus. An example of such a nucleuscontaining both carbonyl and a cyano electron acceptor in thechromophore is represented by the following formula: (XII) ##STR12##where R¹² is aryl, preferably phenyl.

There are, of course, numerous other potential acidic nuclei which canprovide the electron acceptor portion of the dye chromophore. Forexample, the electron acceptor moiety W discussed above can take theform of an acidic nucleus of the type found in merocyanine dyes. In anillustrative form such dyes can be represented by the formula: (XIII)##STR13## where G¹ represents an alkyl group or substituted alkyl group,an aryl or substituted aryl group, an aralkyl group, an alkoxy group, anaryloxy group, a hydroxy group, an amino group, or a substituted aminogroup, wherein exemplary substituents can take the various forms notedin connection with Formulae 1 and 2;

G² can represent any one of the groups listed for G¹ and in addition canrepresent a cyano group, an alkyl, or arylsulfonyl group, or a grouprepresented by ##STR14## or G² taken together with G¹ can represent theelements needed to complete a cyclic acidic nucleus such as thosederived from 2,4-oxazolidinone (e.g , 3-ethyl02,4-oxazolidindione),2,4-thiazolidindione (e.g., 3-methyl-2,4-thiazolidin dione),2-thio-2,4-oxazolidindione (e.g., 3-phenyl-2-thio-2,4-oxazolidindione),rhodanine, such as 3-ethylrhodanine, 3-phenylrhodanine,3-(3-dimethylaminopropyl)rhodanine, and 3-carboxymethylrhodanine,hydantoin (e.g., 1,3-diethylhydantoin and 3-ethyl-1-phenylhydantoin),2-thiohydantoin (e.g., 1-ethyl-3-phenyl-2-thiohydantoin,3-heptyl-1-phenyl-2-thiohydantoin, and arylsulfonyl-2-thiohydantoin),2-pyrazolin-5-one, such as 3-methyl-1-phenyl-2-pyrazolin-5-one,3-methyl-1-(4-carboxybutyl)-2-pyrazolin-5-one, and3-methyl-2-(4-sulfophenyl)-2-pyrazolin-5-one, 2-isoxazolin-5-one (e.g.,3-phenyl-2-isoxazolin-5-one), 3,5-pyrazolidindione (e.g.,1-3,5-pyrazolidin dione and 1,2-diphenyl-3,5-pyrazolidindione),1,3-indandione, 1,3-dioxane-4,6-dione, 1,3-cyclohexanedione, barbituricacid (e.g., 1-ethylbarbituric acid and 1,3-diethylbarbituric acid), and2-thiobarbituric acid (e.g., 1,3-diethyl-2-thiobarbituric acid and1,3-bis(2-methoxyethyl)-2-thiobarbituric acid).

EXAMPLES

The invention can be better appreciated by reference to the followingspecific examples.

Example 1 Preparation of9-Formyl-2,3,6,7-tetrahydro-1H,5H-benzo[i,j]furano[3,2-g]quinolizine##STR15##

Step 1: Preparation of Methyl2,3,6,7-Tetrahydro-1H,5H-benzo[i,j]furano[3,2-g]quinolizin-9-carboxylateTo a 250 mL three necked round-bottom flask equipped with a mechanicalstirrer, reflux condenser, and Y-tube with nitrogen inlet and rubberseptum was added 1.8 gm (45 mmol) of 60% NaH in mineral oil. Afterwashing twice with reagent hexanes, 150 mL of distilled tetrahydrofuran(THF) was added to the flask, followed by the rapid addition, withvigorous stirring, of 4.34 gm (20 mmol) of 9-formyl-8-hydroxyjulolidinein 50 mL of THF. The flask was then placed in an 80° C. oil bath andstirred for several minutes. To the suspension was added in one portion2.08 mL (22 mmol) of methyl bromoacetate. Sodium bromide precipitatedfrom solution and vigorous stirring had to be maintained. The mixturewas refluxed for 8 hours, allowed to cool to room temperature anddiluted with 50 mL of diethyl ether.

The reaction was quenched by slow addition of 50 mL of dilute NH₄ Clsolution. The phases were separated and the aqueous phase extracted with50 mL of Et₂ O. The combined organic phases were washed with 25 mL of 1N NaOH. After washing with water and drying (MgSO₄), the solvent wasremoved by rotary evaporation to yield as a yellow oil. The residue waspurified by flash chromatograPhy (CH₂ Cl₂, SiO₂, 11/2×10") to yield 3.03gm (56%) of the product as a colorless oil: Field desorption massspectrum: m/e 271 (M⁺). ¹ H 270 NMR (CDCl₃):δ1.98 (m, 4H, CH₂ CH₂ CH₂),2.90 (t, 4H, ArCH₂), 3.21 (q, 4H, NCH₂), 3,87 (s, 3H, OCH₃), 7.02 (s,1H, C=CHAr), 7.29 (s, 1H, ArH).

Step 2: Preparation of9-Hydroxymethyl-2,3,6,7-tetrahydro-1H,5H-benzo[i,j]furano[3,2-g]-quinolizine

To a rapidly stirring suspension of 0.21 gm (5.5 mmol) of lithiumtetrahydridoaluminate in 50 mL of distilled THF was added dropwise over10 minutes 3.03 gm (11 mmol) of the compound of Step 1 in 25 mL ofdistilled THF. After stirring for 90 minutes at room temperature, 5 mLof ethyl acetate was added dropwise, followed by the addition of 50 mLof water The phases were separated. The aqueous phase, which containedthe insoluble aluminum salts, was extracted with 50 mL of Et₂ O and thecombined organic phases were washed with 20 mL saturated NaCl solution.After drying (MgSO₄), the solvent was removed by rotary evaporation toyield 2.4 gm (89%) of the product as a colorless oil: Field desorptionmass spectrum: m/e 245 (M⁺). ¹ H 270 NMR (CDCl₃): δ1.7 (s, 1H, OH), 4.66(s, broad, 2H, CH₂ OH), 6.43 (s, 1H, C═CHAr), 7.24 (s, 1H, ArH).

Step 3: Preparation of9-Formyl-2,3,6,7-tetrahydro-1H,5H-benzO[i,j]furano[3,2-g]quinolizine ofStep 1

The compound from step 2 [2.4 gm (10 mmol)] was dissolved in 50 mL ofchloroform and placed in a 200 mL three necked round bottom flaskequipped with a heavy solvent water separator, reflux condenserapparatus, a glass stopcock, and mechanical stirrer. 1.7 gm (20 mmol) ofactive manganese dioxide was added and the suspension refluxed for 1hour. The heat was removed and an additional 1.7 gm of MnO₂ was added.This sequence of MnO₂ addition and hour-long refluxing was continueduntil the reaction was complete by monitoring with thin layerchromatography (3:1 hexanes/EtOAc). The reaction was complete after 5hours, during which time 8.5 gm (100 mmol, 10 equivalents) of additionalmanganese dioxide had been added. The product was isolated as follows: A1/4 inch layer of silica gel was Placed in a 60 mL course sintered glassfunnel and placed on a 500 mL vacuum flask The chloroform suspension waspoured through the silica gel under vacuum and the silica gel was washedwith 300 mL of dichloromethane. The solvent was removed by rotaryevaporation and the resulting residue recrystallized from 40 mL of ethylacetate to yield 1.48 gm (62%) of the desired product as yellow flakes:Field desorption mass spectrum: m/e 241 (M⁺); m.p. 140°-141° C. Anal.calcd. for C₁₅ H₁₅ NO₂ : C, 74.7; H, 6.3; N, 5.8 Found: C, 74.7; H, 6.3;N, 5.8. ¹ H 270 NMR (CDCl₃): δ 7.08 (s, 1H, C═CHAr), 7.33 (s, 1H, ArH),9.53 (s, 1H, CHO). An additional 220 mg was recovered in a secondrecrystallization from ethyl acetate for an overall yield of 69%.

Example 2 Preparation of 6-(N,N-Diethylamino)-2-formylbenzo[b]furan##STR16##

Step 1: Preparation of Methyl 6-(N,N-diethylamino)-2-benzo[b]furanylcarboxylate

To a 250 mL three necked, round bottom flask equipped with a mechanicalstirrer, reflux condenser, and Y-tube with a rubber septum and nitrogeninlet was added 1.8 gm (45 mmol) of 60% sodium hydride in mineral oil.After washing twice with 20 mL of hexanes, 150 mL of THF was added,followed by the rapid dropwise addition via transfer syringe of 3.86 gm(20 mmol) of 4-(N,N-diethylamino)-2-hydroxy benzaldehyde, dissolved in50 mL of tetrahydrofuran (THF). The flask was placed in an 80° C. oilbath and stirred vigorously for 5 minutes, at which time 2.08 mL (20mmol) of methyl bromoacetate was added in one portion. Sodium bromideprecipitated from solution and vigorous stirring had to be maintainedthroughout. The suspension was refluxed for 80 minutes, allowed to coolto room temperature, and diluted with 75 mL of diethyl ether. Thereaction was quenched by the slow dropwise addition of 50 mL of diluteaqueous ammonium chloride. The phases were separated and the aqueousphase extracted with 100 mL of diethyl ether (Et₂ O). The combinedorganic phases were washed with 20 mL 1 N NaOH and 20 mL water. Afterdrying (MgSO₄), the solvent was removed by rotary evaporation and theresidual oil purified by flash chromatography (CH₂ Cl₂ ; SiO₂, 11/2×15")to yield 2.23 gm (45.3%) of the product as a colorless oil. Fielddesorption mass spectrum: m/e 247 (M⁺). Anal. Calcd. for C₁₄ H₁₇ NO₃ C,:68.0; H, 6.9; N, 5.7. Found: C, 67.9; H, 6.8., N, 5.8. ¹ H 270 NMR(CDCl₃): δ6.7 (m, 2H, ArH_(a),b), 7.4 (m, 2H, ArH_(c),d).

Step 2: Preparation of 6-(N,N diethylamino)-2-hydroxymethylbenzo[b]furan

To a rapidly stirring suspension of lithium tetrahydridcaluminate in 100mL of THF was added dropwise over 10 minutes 12.4 gm (50 mmol) of Step 1of this example compound dissolved in 50 mL of ethyl acetate was addeddropwise and the resulting mixture was stirred for 10 minutes. Thesolution was diluted with 75 mL of Et₂ O and 50 mL of water. The phaseswere separated, and the aqueous Phase, which contained the insolublealuminum salts, was extracted with 50 mL of Et₂ O. The combined organicphases were washed with 50 mL saturated NaCl solution, dried (MgSO₄),and the solvent removed by rotary evaporation to yield 9.0 gm (82%) of4b as a pale yellow oil. Purification of an analytical sample by flashchromatography (CH₂ Cl₂ ; SiO₂, 1×10") yielded the product as acolorless oil. Field desorption mass spectrum: m/e 219 (H⁺) Anal calcd.for C₁₃ H₁₇ NO₂ : C, 71.2; H, 7.8; N, 6.4. Found: C, 70.8; H, 7.6; N,6.1. ¹ H 270 NMR (CDCl₃): δ2.2 (s, 1H, OH), 4.62 (s, 2H, CH₂ OH), 6.45(d, 1H, ArH), 6.66 (dd, 1H, ArH), 6.74 (d, 1H, ArH), 7.28 (d, 1H, ArH).

Step 3: Preparation of 6-(N,N-Diethylamino) 2-formylbenzo[b]furan

To a 50 mL round-bottomed flask equipped with a magnetic stirrer andreflux condensor was added 21.9 gm (0.1 mol) of the compound of Step 2of this example, 500 mL of dry carbon tetrachloride, and 27.0 gm (0.11mol) of p-chloranil. After refluxing for 90 minutes, the suspension wasdiluted with 200 mL of dichloromethane. After filtration, the solutionwas washed twice with 100 mL 1N NaOH. The organic phase was dried(MgSO₄), the solvent removed by rotary evaporation and the residuepurified by flash chromatography (6:1 hexanes/EtOAc; SiO₂, 2×18") toyield 15.0 gm (69%) of the product as a yellow oil Field desorption massspectrum: m/e 217s (M⁺). Anal. calcd. for C₁₃ H₁₅ NO₂ : C, 71.9; H, 7.0;N, 6.4. Found: C, 71.8., H, 7.0; N, 6.3. ¹ H 270 NMR (CDCl₃): δ6.69 (d,1H), 6.74 (dd, 1H), 7.37 (d, 1H), 7.46 (d, 1H), 9.58 (s, 1H).

The new dyes of this invention are prepared by condensation of the newintermediates of Examples 1 and 2 in pyridine with an active methylenecompound such as 3-cyano-4-phenyl-2-furanone, cyclopentanone,4-dicyanomethylene-2,6-dimethyl-4H-pyran, 3-acetyl7-(N,N-dialkylamino)coumarins and the like.

The following examples illustrate the condensation of the intermediatewith an active methylene compound to produce the dyes of the invention.

Example 3 Preparation of3-Cyano-4-phenyl-5-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]-furano[3,2-g]quinolizin-9-yl-methylene)-2-furanone,Dye 1, Table I

To 3 mL of pyridine in a 10 mL round bottomed flask was added 120 mg(0.5 mmol) of the compound of Example 1 and 80 mg (0.5 mmol) of3-cyano-4-phenyl-2-furanone. The solution was heated at 80° C. for 3hours, cooled and poured into 20 mL dilute NH₄ Cl. The resulting mixturewas extracted 2X with 20 ml 3:2 hexanes/Et₂ O and the combined organicextracts washed once with 10 mL of water. The organic phase was dried(MgSO₄) and the solvent removed by rotary evaporation. The resultingsolid was puridied by flash chromatography (7:2 cyclohexane/EtOAc; SiO₂,1×12") to yield 40 mg (22%) of Compound 6, Table I. Field desorptionmass spectrum: m/e 408 (M⁺); m.p 231°-32° C. Anal calcd. for C₂₆ H₂₀ N₂O₃ : C, 76.4; H, 4.9; N, 6.9. Found: C, 76.1; H, 4.7; N, 6.8.

Example 4 Preparation of 3-Cyano-5-[6-(N,Ndi-ethylamino)benzo[blfuranylmethvlene]4-phenyl 2-furanone, Dye 2, TableI

To 5 mL of pyridine in a 15 mL round bottom flask was added 217 mg (1mmol) of the compound of Example 2 and 172 mg (1 mmol) of3-cyano-4-phenyl-2-furanone. The solution was heated at 80° C. for onehour, colled and poured into 20 mL dilute NH₄ Cl. The resulting mixturewas extracted 2X with 20 mL 3:2 hexanes Et₂ O and the combined organicextracts were washed once with 10 mL of water, The organic phase wasdried (MgSO₄) and the solvent removed by rotary evaporation. Theresulting solid was purified by flash chromatography (7:2cyclohexane/EtOAc; SiO₂, 1×12") to yield 292 mg of dye. Anal. calcd. forC₂₄ H₂₀ N₂ O₃ : C, 74.2; H, 5.4; N, 7.5. Found: C, 74.0l H, 5.2; N, 6.9.

Example 5 Preparation of7-N,N-Diethylamino-3-{3-[6-(N,N-diethylamino)benzo[b]furanyl]acryloyl}coumarin, Dye 3. Table I

To 25 mL of absolute ethanol in a 50 mL round bottomed flask was added217 mg (1 mmol) of 6-(N,N-diethylamino)-2-formylbenzo[b]furan and 259 mg(1 mmol) of 3-acetyl-7-(N,N-diethylamino)coumarin. After refluxing forseveral minutes to dissolve the solids, 100 mg of piperidine was addedand reflux was continued for one hour. The solution was allowed to coolto room temperature and then placed in a freezer overnight. The solidwas filtered and recrystallized from 50 mL of ethanol to yield theproduct as deep red needles. Field desorption was spectrum: m/e 458(M⁺); m.p. 169°-171° C.

Example 6 Preparation of 9-[3-(2,3,6,7-Tetrahydro1H,5H-benzo[i,j]furano[3.2-g]-quinolizin-9-yl)acryloyl]-1,2,4,5-tetrahydro-3H,6H,10H[1]benzopyrano[9,9a1-gh]quinolazin-10-one,Dye 4, Table I

To 25 mL of absolute ethanol in a 50 mL round bottomed flask was added241 mg (1 mmol) of the compound of Example 3 and 283 mg (1 mmol) of3-acetyl-7-(N,N-diethylamino)coumarin. After refluxing for severalminutes to dissolve the solids, 100 mg of piperidine was added andreflux was continued for two hours. The solution was allowd to cool andthe solid filtered to yield 450 mg (89%) of product as black needles.Field desorption mass spectrum: m/e 506 (M⁺), m.p. 242°-244° C.

Example 7 Preparation of 4-(Dicyanomethylene)-2-methyl-6-[2-(N,N-diethylamino)benzo[b]furanyl]ethenyl-4H-pyran. Dye 5. Table I

To 10 mL of toluene in a 25 mL round-bottom flask was added 217 mg (1mmol) of the aldehyde of Example 2, 172 mg (1 mmol) of4-(dicyanomethylene)-2,6-dimethyl 4H-pyran, 85 mg of piperdine, and 60mg of glacial acetic acid. The solution was refluxed for 30 minutes andanother 85 mg of piperdine and 60 mg of acetic acid were added. Afterrefluxing for an additional 30 minutes, the reaction mixture was cooled,diluted with 50 mL Et₂ O, and washed with 10 mL saturated NaHCO₃followed by 10 mL of water. The organic phase was dried (MgSO₄) and thesolvent removed by rotary evaporation to yield 0.39 g of a purple solid.Flash chromatorgaphy (7:2 cyclohexane/EtOAc; SiO₂, 1×12") yielded 160 mg(43%) of Dye 5 as a brown solid: Field desorption mass spectrum: m/e 371(M+); m.p. 218°-220° C. Anal. calc'd for C₂₃ H₂₁ N₃ O₂ : C, 74; H, 5.9;N, 9.8. Found: C, 74.0; H, 5.7; N, 10.3.

Example 8 Preparation of4-(Dicyanomethylene)-2-methyl-6-[2-(2,3,6,7-tetrahydro)-1H,5H-benzo[i]furano[3,2-g]quinolizin-9-yl]ethenyl-4H-pyran,Dye 6. Table I

To 5 mL of toluene in a 15 mL round bottom flask was added 100 mg of(0.4 mmol) of the aldehyde of Example 1, 78 mg (0.45 mmol) of4-(dicyanomethylene) 2,6-dimethyl-4H-pyran, 20 mg of piperdine, and 20mg of glacial acetic acid. The solution was refluxed for 3 hours,cooled, and poured through a 0.64 cm pad of silica gel into a vacuumflask. The silica gel was washed with dichloromethane until all colorwas removed. The solvent was removed by rotary evaporation and theresidue was purified by flash chromatography (7:2 cyclohexane/EtOAc;SiO₂, 1 X 12") to yield 40 mg of (25%) of Dye 6 as a deep red solid:Field desrption mass spectrum: m/e 395 (M+); m.p. 247°-249° C. Anal.calc'd. for C₂₅ H₂₁ N₃ O₂ : C, 75.6; H, 5.3; N, 10.5. Found: C, 75.3; H,5.2; N, 10.3.

Example 9 Preparation of2.5-Bis[6-(N,N-diethylamino)benzo[b]-2-furanylmethylene]cyclopentanone,Dye 7, Table I

A solution of 370 mg (1.7 mmol) of the aldehyde of Example 2 and 72 mg(0.085 mmol) of cyclopentanone in 15 mL of 2N methanolic KOH wasrefluxed for 11/2 hours. The solution was cooled to room temperature andthe product was filtered, washed with MeOH (yield 290 mg, 72%) andrecrystallized from a cyclohexane/toluene mixture. The compound issolvatochromic with an absorption maximum of 565 nm in methanol.

Example 10 Preparation of2,5-Bis(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]furano[3,2-g]-quinolizin-9-yl-methylene)cyclopentanone,Dye 8, Table I

This compound was prepared as described for Example 7 except using theintermediate of Example 1. It has an absorption maximum of 590 nm inmethanol.

Example 11 Preparation of 8(p-methoxyphenacyloxy)julolidine

A mixture of 4.65 g (0.025 M) of 8-hydroxyjulolidine. 5.50 g (0.024 M)of p-(methoxy)Phenacyl bromide and 3.45 g (1 equiv.) of potassiumcarbonate in 30 mL of acetone and 15 drops of water was refluxedovernight. The reaction mixture was poured in water and extracted withether. The ether extract was dried (MgSO₄), rotary evaporated and theresidue was purified by flash chromatography to give 5.82 g (72%) ofproduct: F.D. m/e 337 (M⁺); Anal. Calc'd for C₂₁ H₂₃ NO₃ : C, 74.8; H,6.9; N, 4.2. Found: C, 73.9; H, 6.8, N, 4.0.

Example 12 Preparation of 8 (p-methoxyphenyl) 2,3,6,7-tetrahydro-1H,5Hbenzo[i,j]furano[3.2-quinolizine

A mixture of 5.52 g (0.0164M) of 8-(p-methoxyphenacyloxy)julolidine and1.36 g (0.01 M) of zinc chloride in 10 mL of ethanol was refluxed for 4hours. The reaction mixture was poured into dilute HCl and extractedwith methylene chloride. The extracts were washed with water, dried(MgSO₄), rotary evaporated. The residue was recrystallized from hexanesand a small amount of ethyl acetate to give 2.85 g (55%) of product:F.D. m/e 319 (M⁺); Anal. Calc'd. for C₂₁ H₂₁ NO₂ : C, 79.0; H, 6.6; N,4.4. Found: C, 78.0; H, 6.6; N, 4.2.

Example 13 Preparation of 9-Formyl-8-(p-methoxyphenyl)-2,3,6,7tetrahydro-1H.5H benzo [i,j]furano[3,2-g]quinolizine

A Vilsmeir reagent was prepared by mixing 0.223 g (1.5 mmol) ofphosphoryl chloride and 1 mL of DMF and stirring at room temperature for1 hour. To the Vilsmeir reagent was added 0.32 g (1 mmol) of the productfrom Example 12. The reaction mixture was heated at 50° C. for 10minutes, poured into aqueous sodium acetate, and extracted withmethylene chloride. The extracts were dried (MgSO₄), rotary evaporatedand flash chromatographed to give 268 mg (77%) of product: F.D. m/e 347(M⁺); Anal. Calc'd. for C₂₂ H₂₁ NO₃ : C, 76.1; H, 6.1; N, 4.0. Found: C,75.7; H, 5.7; N, 3.7.

Example 14 Preparation of3-Cyano-4-phenyl-5-[8-(p-methoxyphenyl)-2,3,6,7-tetrahydro-1H,5H-benzo[i,j]furano[3,2-g]quinolizin-9-yl-methylene]-2-furanone,Dye 10, Table I

A mixture of 52 mg (0.15 mmol) of the aldehyde from Example 13 and 27 mg(1 equiv.) of 3-cyano-4-phenyl-2-furanone in 0.7 mL of pyridine washeated at 90° C. for 2 hours. To the hot reaction mixture were added 12mL of acetonitrile, and the mixture was brought to reflux for 5 minutes.Dye 10 crystallized on cooling to give 50 mg (67%) of crystals: F.D. m/e514 (M⁺); Anal. Calc'd. for C₃₃ H₂₆ N₂ O₄ : C, 77.0; H, 5.1; N, 5.4.Found: C. 75.9; H, 5.1; N, 5.4.

In Table I are listed representative dyes according to the invention andthe effectiveness of the 6 tertiary aminobenzofuran nucleus inbathochromically shifting the maximum absorption wavelength of the dyesof this invention is illustrated by comparing the maximum absorptions ofthese dyes with dyes containing structurally similar nuclei.

                                      TABLE I                                     __________________________________________________________________________     ##STR17##                                                                    __________________________________________________________________________                                                Com- λ-max                 D.sup.1                                     pound                                                                              nm (CH.sub.2 Cl.sub.2)                                                                  ε(10.su                                                               p.3)               __________________________________________________________________________     ##STR18##                                  Dye 1                                                                              655       52                  ##STR19##                                  Dye 2                                                                              613       33                  ##STR20##                                  Control                                                                            537       50                  ##STR21##                                  Control                                                                            565       44                  ##STR22##                                  Control                                                                            570       65                  ##STR23##                                  Dye 9                                                                              620       53                  ##STR24##                                  Dye 10                                                                             660       55                  ##STR25##                                  Dye 11                                                                             696       49                 __________________________________________________________________________                                                Com- λ-max                 Complete Dye Structure                      pound                                                                              nm (CH.sub.2 Cl.sub.2)                                                                  ε(10.su                                                               p.3)               __________________________________________________________________________     ##STR26##                                  Control                                                                            415       38                  ##STR27##                                  Control                                                                            430       38                  ##STR28##                                  Dye 3                                                                              445 495 (C.sub.6                                                              H.sub.6)  31 50               ##STR29##                                  Dye 4                                                                              461 511 (C.sub.6                                                              H.sub.6)  32 52               ##STR30##                                  Dye 5                                                                              517       48                  ##STR31##                                  Dye 6                                                                              540       38                  ##STR32##                                  Dye 7                                                                              513 (Cyclohexane 632                                                          (Toluene) 538                                                                 (Acetonitrile) 565                                                            (Methanol)                                                                              89 67 59 54         ##STR33##                                  Dye 8                                                                              530 (Cyclohexane) 542                                                         (Ethyl acetate) 590                                                           (Methanol)                   __________________________________________________________________________

The utility of the dyes of the invention as free radical polymerizationcoinitiators can be appreciated by reference to Specht et al U.S. Pat.Nos. 4,289,844 and 4,278,751 and published U.K. Spec. No. 2,083,832A;Guild U.S. Pat. No. 4,247,623; and Klein et al U.S. Ser. No. 77,714,filed July 24, 1987, now U.S. Pat. No. 4,792,517. The dyes havingfluorescent properties can be substituted for conventional dyes. Onepreferred application for the fluorescent dyes is in organicelectroluminescent cells. The fluorescent dyes of this invention can besubstituted for any of those disclosed for use in organicelectroluminescent cells by Tang U.S. Ser. No. 20,408, filed Mar. 2,1987, now abandoned in favor of U.S. Ser. No. 108,342, filed Oct. 14,1987, which has issued as U.S. Pat. No. 4,769,292.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

What is claimed is:
 1. A dye which satisfies the formula: ##STR34##where R¹, R², and R⁵ each independently represent hydrogen, alkyl, oraryl;R³ and R⁴ each independently represent alkyl; or at least one ofthe substituent pairs represented by R¹ and R⁴, R² and R³, and R³ and R⁴complete a 5- or 6-membered ring containing the formula nitrogen atom asthe sole heteroatom; W¹ represents ##STR35## and R¹³ represents a3-coumarinyl group; alkyl in each occurrence containing from 1 to 8carbon atoms and aryl in each occurrence being phenyl or naphthyl.
 2. Adye according to claim 1 in which the 3-coumarinyl group satisfies theformula: ##STR36## where R⁶ and R⁷ each independently representhydrogen, alkyl, or aryl;R⁸ and R⁹ each independently represent alkyl;or at least one of the substituent pairs represented by R⁶ and R⁹, R⁷and R⁸, and R⁸ and R⁹ complete a 5- or 6-membered ring containing theformula nitrogen atom as the sole heteroatom; alkyl in each occurrencecontaining from 1 to 8 carbon atoms and aryl in each occurrence beingphenyl or naphthyl.
 3. A dye according to claim 6 in which R⁶, R⁷, R⁸,and R⁹ complete a julolidine ring structure.
 4. A7-(N,N-dialkylamino)-3-{3-[6-(N,N-dialkylamino)benzo[b]furanyl]acryloyl}coumarin.5.9-[3-(2,3,6,7-Tetrahydro-1H,5H-benzo-[i,j]furano[3,2-g]quinolinizin-9-yl)acryloyl]-1,2,4,5-tetrahydro-3H,6H,10H[1]benzopyrano[9,9a,1-gh]quinolazin-10-one.